There has been known a technology wherein there is used a special sheet group in which plural special sheets each being different in terms of a kind such as plural tab sheets each being different in terms of tab position or plural color sheets each being different in terms of color, are arranged in the predetermined order to form one set, in an image forming apparatus such as a copying machine or a printer, and special sheets are inserted in established pages in the course of printing, to make printed objects. In the generation of printed objects employing the special sheets as stated above, a right sheet needs to be inserted in a right position.
Namely, in generation of printed objects employing a group of special sheets, the special sheets need to be inserted in the predetermined order in sequence from the forefront of the printed objects each having thereon images formed. However, when the number of special sheets used for printing for one printed object is not an integral multiple of the number of special sheets per one set, unwanted special sheets are generated each time printing of one printed object is completed. For example, when one set shown in FIG. 10(a) uses a group of tab sheets in 5-tab structure, and printing for the first printed object is carried out by setting an insertion position of a tab sheet in each printed object to be “after obverse cover/back cover/2 pages”, tab sheets up to the third tab are used. If the second printed object is printed without taking any action, a tab sheet of the fourth tab is inserted as an obverse cover, which is a trouble.
To solve this trouble, therefore, there has been disclosed a technology wherein, when the number of tabs to be used for one printed object, for example, is not an integral multiple of the number of tab positions, namely, the number of sheets with tabs constituting one set, the excessive sheets each having a tab are ejected (for example, see Patent Document 1).
For example, as shown in FIG. 9, when conducting printing by using a group of tab sheets in which one set is composed of 5 tabs, and by setting an insertion position for a tab sheet in each printed object to be “after obverse cover/back cover/second page”, a tab sheet can be inserted correctly even when printing the following printed object, by ejecting unwanted tab sheets equivalent to two sheets of fourth and fifth tabs, after completion of printing of one printed object and before the start of the following printing.
There is further disclosed a technology wherein judgment is made whether or not the excessive tab sheets are generated from the number of tab sheets for one set and the number of tab sheets to be inserted, and when excessive tab sheets are generated, the unwanted tab sheets are ejected to a place other than a default tray, after selection of sheet-ejection tray is made impossible (for example, see Patent Document 2).
Furthermore, there is disclosed a technology wherein those ejected as unwanted tab sheets are used as a divider for each printed object, for resource saving (for example, see Patent Document 3).
(Patent Document 1) Patent No. 2728812
(Patent Document 2) TOKUKAI No. 2002-3063
(Patent Document 3) TOKUKAI No. 2003-40517
However, in some cases, there are provided some “paragraphs” which divide each “chapter” into smaller parts, in addition to “chapter” serving as a large partition, in the printed objects, and tab sheets each being different each other in type are inserted in respective partitions. Since each of the aforesaid Patent Documents 1-3 is one wherein a special sheet is ejected in the case of using a group of special sheets of one type, it is not possible to eject properly unwanted special sheets when using a group of special sheets of plural types, and an order of special sheets to be inserted in printed objects is disturbed, which has been a problem.
For example, when a group of tab sheets in 3-tab structure for one set and a group of tab sheets in 5-tab structure for one set are used as shown in FIG. 11(a), and a group of tab-sheets in 3-tab structure is used as a divider of “chapter” and a group of tab-sheets in 5-tab structure is used as a divider of “paragraph”, tab sheets are inserted as shown in FIG. 11(b) in the conventional technology. Namely, FIG. 11 shows how tab sheets are inserted, when generating printed objects under the condition that an insertion position of a tab sheet of a group of tab sheets in 3-tab structure in each copy is set to be “cover/after fifth page/after tenth page”, and an insertion position of a tab sheet of a group of tab sheets in 5-tab structure is set to be “after first page/after third page/after sixth page/after eighth page/after eleventh page/after thirteenth page”. In this case, as shown in FIG. 11(b), a group of tab sheets in 5-tab structure does not return to the tab sheet of the first tab until all of five tab sheets are used up, even when printing of each chapter is terminated and second sheet of a group of tab sheets in 3-tab structure is inserted. Therefore, paragraph 1 and paragraph 2 of chapter 2 of the printed object become respectively third tab and fourth tab in 5-tab structure, while, paragraph 1 and paragraph 2 of chapter 3 become respectively fifth tab (first set) and first tab (second set) in 5-tab structure.